It is well known in the art, that changing the angularity of the shaft axis in relation to the golf club head changes important playing characteristics such as the loft angle of the face and lie angle. Face loft angle is generally considered to be the angle between the plane of the face, or tangent plane to the center of the face if the face is not flat, and the shaft axis. The lie angle is generally considered to be the angle between a plane parallel to the ground, and tangent to the sole center, and the shaft axis. In addition, more particularly in wood type clubs, the shaft axis angularity also changes the face angle at address, the face angle considered to be the angle between a vertical plane passing through a line normal to the face surface center and perpendicular to the ground plane and a plane perpendicular to a vertical plane passing through the shaft axis and perpendicular to the ground plane. Altering these angles changes the way a club head reacts with a golf ball at impact making ball flight higher or lower, or more apt to fly to the right or left depending on the direction and magnitude of the angle variations. Since individuals swing golf clubs differently, and present the club head to the ball in varying attitudes and directions, setting the position of the golf club head in relation to the shaft axis in a more optimum orientation can facilitate dramatic improvements in ball flight for a given individual.
Golf clubs have been typically manufactured with separate club heads, shafts and grips. These three main components are generally fixed together before sale, the grip attached to the shaft by means of sliding over a layer of double face tape wetted with a solvent, and the head to the shaft by means of shaft insertion into a hole in the head and an epoxy bond. Using these conventional methods the angularity of the head and shaft are permanently fixed and cannot be easily altered.
In wood type clubs where tube like extensions to the heads called hosels contain part or all of the shaft bore holes, these hosels can be bent to alter the shaft axis angle to the head. However, this requires special tools and elaborate fixtures to hold the head while bending the hosel and can easily damage or break the head. In this conventional assembly arrangement, changing the shaft requires the epoxy bond to be broken with the application of heat. Since many of today's driver and wood shafts are of graphite composite construction, the epoxy bond must be carefully heated and the shaft pulled by a special apparatus designed not to twist the shaft while extracting.
Because of the great difficulty in altering the shaft orientation to the club head, as well as interchanging the shafts themselves, manufacturers and been forced to produce a wide range of individual clubs exhibiting different face angles and loft angles along with different shaft types to better accommodate the preference and skill level of the individual golfer. The result being increased manufacturing cost due to multiple tooling as well as increased inventory and stock keeping units (SKUs) for both manufacturer and retailer.
Most prior art has resorted to a means of off angle shaft bore rotation to change the orientation of the shaft axis to the golf club head. These designs rely on a spline or other method of rotation fixation along with a fastener such as a hold down bolt or compression clamping nut to lock the assembly in place. These methods have several short comings which the present invention overcomes. The prior art methods of off angle bore rotation require the face angle and lie angle to be simultaneously changed during rotation. To close the face angle from a neutral position, the lie angle must become either flatter or more upright. Likewise, to open the face angle, the lie angle must again become either flatter or more upright. This is the result of the off angle bore axis sweeping through a conical shape surface as it rotates. Another shortcoming of the off angle bore rotation method is that the shaft and grip together must rotate into a new clock position. This introduces certain inconsistencies caused by shaft straightness and shaft bending differences based on clock position sometimes referred to as a shaft spine. This method must use a round grip and prevents the use of a reminder grip design as well as traditional grip graphics that aid the golfer in repeating grip location. Still another short coming of the prior art designs is a finite number of adjustments within the adjustment range. Using a spline or other rotation limiting methods, the adjustments are limited to the number of teeth or other such segments on the clocking mechanism.
The present invention seeks to solve the above short comings of the prior art by allowing the face angle of a wood type club to be changed independently of lie angle and without the shaft and grip assembly rotating to a different clock position. The invention also allows an infinite number of positions to be attained within its range of motion of adjustment. The present invention also allows fast and easy shaft/grip assembly interchangeability to customize shaft type for an individual.
One example of the prior art is U.S. Pat. No. 7,083,529 B2 to Cackett et al. for a Golf Club with Interchangeable Head-Shaft Connections. The Cackett patent discloses two interconnected tubes, the bottom tube is secured in the club head by suitable means, the upper tube fits inside of the bottom tube and interconnects by means of complimentary interacting surfaces on the bottom tip such as a spline along with a matching tapered section above the spline to provide a tight rattle free fit. The upper tube is bored from the top for insertion and bonding of a golf shaft and is held in place by a mechanical fastener such as a screw entering from the bottom sole and threaded into the bottom section containing the spline. The arrangement is an effort to reduce material weight and provide a means of quick shaft interchangeability.
Another example of the prior art, U.S. Publ. Pat. App. No. US 2006/0287125 A1, discloses a similar arrangement to U.S. Pat. No. 7,083,525 to Cackett but adds a shaft axis bore in the upper tube that is off angle to the axis of the bottom tube. This off angle embodiment allows for the rotation and fixation of the shaft carrying upper tube and thus alterations in the loft, face angle, and lie of the club head. However, this arrangement leaves the angular alterations of the head and shaft axis interconnected and dependent upon one another, not allowing independent change of any of these angles.
Still another example of the prior art, U.S. Pat. No. 5,390,920 to Nickum, depicts and adjustable head with the lower most end of the shaft terminating in a sphere or pivot ball. The sphere is enclosed in an internal bore and engaged from the bottom side by a clamping screw that compresses and locks the sphere in place when tightened. The shaft and sphere can freely rotate when the clamping screw is loosened. This example provides no positive indexing method for shaft angle location and relies solely on the friction between the sphere and clamping surfaces to hold position during impact, something not realistic for anything other than a putter type club.
Yet another example of the prior art, U.S. Pat. No. 6,368,230 to Helmstetter, shows an off angle rotating sleeve inserted into a wood type golf head with indexing detents to locate the clock position of the sleeve and thus the shaft axis position. Again as with all rotating off angle systems, the lie and face angles are interdependent upon each other, and also requires the shaft to clock as the off angle bore rotates.